Two-time major championship winner John Daly will be the subject of a new ESPN "30 for 30" documentary, "Hit It Hard." Photo: AP

In 1997, John Daly already was a two-time major championship winner with more fame and fortune than almost anyone in golf ever had attained.

Yet he sat alone in his Mercedes on the edge of a cliff in Palm Springs, Calif., revving the engine, readying to end his life.

“I was two feet away from doing it,’’ Daly told The Post in an interview in advance of Tuesday’s premiere of “Hit It Hard,” an ESPN “30 for 30’’ documentary about his life.

“I had been struggling to see my [first] kid, Shynah; that was the whole focus. And the PGA Tour was making me go to rehab, so I was being forced to do something I don’t want to do. I wasn’t used to the success. I wasn’t ready for it. It was tough time in my life.’’

Former Dallas Cowboys player Thomas “Hollywood” Henderson in 2000Photo: AP

“I’m in bed at home and my phone rings, and it’s John Daly, and I hear the gunning of an engine,’’ former NFL star Thomas “Hollywood’’ Henderson recalled in the documentary. “He said, ‘I’m on a mountaintop.’ I said, ‘What do you mean?’ He said, ‘There will be no more John Daly tomorrow.’

“I started to cry, and I said, ‘You can’t do this. The world is not done with John Daly yet.’ ’’

Daly met Henderson for the first time in 1992, during his first stint in alcohol rehab. Henderson, after living a wild life as an NFL player, had gotten clean and devoted his life to counseling people facing the same demons he once did.

“His things in his life related to a lot of things I was going through in my life,’’ Daly said. “He just said the right things.’’

Maybe that’s why it was Henderson to whom Daly, who turned 31 that year, would make that last desperate phone call before he would pop his Mercedes into gear and drive off that cliff.

“I said, ‘John, will you do me a favor? I’ve never asked you to do anything for me,’ ’’ Henderson said.

John Daly, with his son, John Jr., and then-wife Sherri, celebrates after winning the 2004 Buick Invitational at Torrey Pines.Photo: WireImage

“I said, ‘Go home,’ ’’ Henderson went on, his voice cracking with emotion at the memory. “So he went home.’’

Recalling his emotions on the ride home that night after Henderson talked him out of killing himself, Daly said, “I felt relieved. There are people that care.

“If there was anybody that was my big brother in this, it was Thomas. No matter how many meetings I went to, I got tired of talking about alcohol. The more you talk about it, the more you just want to go to a bar and get drunk.’’

Daly’s private brush with suicide stands out among the many manic highs and dire lows experienced in a life lived so publicly:

Daly improbably winning the 1991 PGA Championship at Crooked Stick after he had gotten into the field as the ninth and final alternate.

Daly capturing the 1995 British Open at St. Andrews, validating himself as a two-time major champion.

His four wives (who became ex-wives), three kids by three different mothers and messy custody fights.

His peddling of personal merchandise from his RV parked across Washington Road from the gates of Augusta National during the Masters.

“I’ve screwed up a lot, but I’ve always admitted it,’’ Daly told The Post. “Looking at my downs in life, it’s incredible that I’m still here, to be honest with you. I never thought I’d see 50.’’

Does he still drink? “I drink every now and then, but … I still monitor it,’’ Daly said. “I’m not one of those guys where if something goes bad, I’m going to just go out and get drunk like I used to.’’

Does he still gamble? “Very little,’’ Daly said. “I’m not a big gambler anymore. I like to do it. I enjoy it instead of trying to make money off of it, because I realized you can’t make money gambling.’’

The millions he lost gambling? “I look it as, hey, it was a great time,’’ Daly said. “I have to look at it that way, otherwise be beating myself up about it.’’

Asked what he would do with the $50 million if he had it now, Daly said, “Probably put $5 million in my account and give the other $45 million to my kids.’’

Daly traces his descent in life to that first ascent at the ’91 PGA.

“My life changed in four days,’’ he recalled. “I wasn’t ready for the aftermath of it. All this money started coming and all these hands were out and I didn’t know how to deal with it. I was like, ‘Screw this, I’m just going to go to a bar and get drunk.’

“I’d get so drunk I couldn’t even talk. I didn’t want to talk to anyone, so I figured the drunker I got, nobody’s going to want to be around me.’’

He revels in what he’s accomplished but refuses to lament what he left on the table because of his numerous missteps.

“I look at the PGA and it was like winning the lottery,’’ Daly said. “The British Open was like proving myself.’’

John Daly plays in the Toshiba Classic in Newport Beach, Calif., in October 2016.Photo: Getty Images

He believes the major misconception about him is this: “That maybe I don’t care when I really do.’’

“Walking off courses and doing the stupid stuff that I did, I think I lost a lot of respect from the players,’’ Daly said. “With a lot of them, I think I’ve gotten the respect back because a lot of them appreciate the hard work I’ve done to try and get better and do better. But a lot of them I understand I don’t have their respect back. I have to live with that and it hurts.

“That’s probably one of the reasons why I haven’t been on a Ryder Cup and probably will never be a captain of a Ryder Cup.’’

Daly, now 50 and playing on the Champions Tour, is engaged to Anna Cladakis, who often caddies for him in tournaments, and he relishes what he calls a more “normal’’ life.

One thing Daly never has lost is the love and support of the fans, whom he called “my distant family.’’

“The fans have always helped me get through good things and bad things on and off the golf course,’’ he said. “I’ve always believed no matter where I’ve played — and even now on the Champions Tour — I feel like it’s a home-field advantage for me.’’

Of his well-worn life, Daly said: “I know there were a lot of lows, but the lows cannot defeat me and they cannot defeat the highs I’ve had in my life. I kind of like the way it’s turned out.’’